/*
 * Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 */

package java.util;

import java.text.DateFormat;
import java.time.LocalDate;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.lang.ref.SoftReference;
import java.time.Instant;
import sun.util.calendar.BaseCalendar;
import sun.util.calendar.CalendarDate;
import sun.util.calendar.CalendarSystem;
import sun.util.calendar.CalendarUtils;
import sun.util.calendar.Era;
import sun.util.calendar.Gregorian;
import sun.util.calendar.ZoneInfo;

/**
 * The class <code>Date</code> represents a specific instant
 * in time, with millisecond precision.
 * <p>
 * Prior to JDK&nbsp;1.1, the class <code>Date</code> had two additional
 * functions.  It allowed the interpretation of dates as year, month, day, hour,
 * minute, and second values.  It also allowed the formatting and parsing
 * of date strings.  Unfortunately, the API for these functions was not
 * amenable to internationalization.  As of JDK&nbsp;1.1, the
 * <code>Calendar</code> class should be used to convert between dates and time
 * fields and the <code>DateFormat</code> class should be used to format and
 * parse date strings.
 * The corresponding methods in <code>Date</code> are deprecated.
 * <p>
 * Although the <code>Date</code> class is intended to reflect
 * coordinated universal time (UTC), it may not do so exactly,
 * depending on the host environment of the Java Virtual Machine.
 * Nearly all modern operating systems assume that 1&nbsp;day&nbsp;=
 * 24&nbsp;&times;&nbsp;60&nbsp;&times;&nbsp;60&nbsp;= 86400 seconds
 * in all cases. In UTC, however, about once every year or two there
 * is an extra second, called a "leap second." The leap
 * second is always added as the last second of the day, and always
 * on December 31 or June 30. For example, the last minute of the
 * year 1995 was 61 seconds long, thanks to an added leap second.
 * Most computer clocks are not accurate enough to be able to reflect
 * the leap-second distinction.
 * <p>
 * Some computer standards are defined in terms of Greenwich mean
 * time (GMT), which is equivalent to universal time (UT).  GMT is
 * the "civil" name for the standard; UT is the
 * "scientific" name for the same standard. The
 * distinction between UTC and UT is that UTC is based on an atomic
 * clock and UT is based on astronomical observations, which for all
 * practical purposes is an invisibly fine hair to split. Because the
 * earth's rotation is not uniform (it slows down and speeds up
 * in complicated ways), UT does not always flow uniformly. Leap
 * seconds are introduced as needed into UTC so as to keep UTC within
 * 0.9 seconds of UT1, which is a version of UT with certain
 * corrections applied. There are other time and date systems as
 * well; for example, the time scale used by the satellite-based
 * global positioning system (GPS) is synchronized to UTC but is
 * <i>not</i> adjusted for leap seconds. An interesting source of
 * further information is the U.S. Naval Observatory, particularly
 * the Directorate of Time at:
 * <blockquote><pre>
 *     <a href=http://tycho.usno.navy.mil>http://tycho.usno.navy.mil</a>
 * </pre></blockquote>
 * <p>
 * and their definitions of "Systems of Time" at:
 * <blockquote><pre>
 *     <a href=http://tycho.usno.navy.mil/systime.html>http://tycho.usno.navy.mil/systime.html</a>
 * </pre></blockquote>
 * <p>
 * In all methods of class <code>Date</code> that accept or return
 * year, month, date, hours, minutes, and seconds values, the
 * following representations are used:
 * <ul>
 * <li>A year <i>y</i> is represented by the integer
 * <i>y</i>&nbsp;<code>-&nbsp;1900</code>.
 * <li>A month is represented by an integer from 0 to 11; 0 is January,
 * 1 is February, and so forth; thus 11 is December.
 * <li>A date (day of month) is represented by an integer from 1 to 31
 * in the usual manner.
 * <li>An hour is represented by an integer from 0 to 23. Thus, the hour
 * from midnight to 1 a.m. is hour 0, and the hour from noon to 1
 * p.m. is hour 12.
 * <li>A minute is represented by an integer from 0 to 59 in the usual manner.
 * <li>A second is represented by an integer from 0 to 61; the values 60 and
 * 61 occur only for leap seconds and even then only in Java
 * implementations that actually track leap seconds correctly. Because
 * of the manner in which leap seconds are currently introduced, it is
 * extremely unlikely that two leap seconds will occur in the same
 * minute, but this specification follows the date and time conventions
 * for ISO C.
 * </ul>
 * <p>
 * In all cases, arguments given to methods for these purposes need
 * not fall within the indicated ranges; for example, a date may be
 * specified as January 32 and is interpreted as meaning February 1.
 *
 * @author James Gosling
 * @author Arthur van Hoff
 * @author Alan Liu
 * @see java.text.DateFormat
 * @see java.util.Calendar
 * @see java.util.TimeZone
 * @since JDK1.0
 */
public class Date
    implements java.io.Serializable, Cloneable, Comparable<Date> {

  private static final BaseCalendar gcal =
      CalendarSystem.getGregorianCalendar();
  private static BaseCalendar jcal;

  private transient long fastTime;

  /*
   * If cdate is null, then fastTime indicates the time in millis.
   * If cdate.isNormalized() is true, then fastTime and cdate are in
   * synch. Otherwise, fastTime is ignored, and cdate indicates the
   * time.
   */
  private transient BaseCalendar.Date cdate;

  // Initialized just before the value is used. See parse().
  private static int defaultCenturyStart;

  /* use serialVersionUID from modified java.util.Date for
   * interoperability with JDK1.1. The Date was modified to write
   * and read only the UTC time.
   */
  private static final long serialVersionUID = 7523967970034938905L;

  /**
   * Allocates a <code>Date</code> object and initializes it so that
   * it represents the time at which it was allocated, measured to the
   * nearest millisecond.
   *
   * @see java.lang.System#currentTimeMillis()
   */
  public Date() {
    this(System.currentTimeMillis());
  }

  /**
   * Allocates a <code>Date</code> object and initializes it to
   * represent the specified number of milliseconds since the
   * standard base time known as "the epoch", namely January 1,
   * 1970, 00:00:00 GMT.
   *
   * @param date the milliseconds since January 1, 1970, 00:00:00 GMT.
   * @see java.lang.System#currentTimeMillis()
   */
  public Date(long date) {
    fastTime = date;
  }

  /**
   * Allocates a <code>Date</code> object and initializes it so that
   * it represents midnight, local time, at the beginning of the day
   * specified by the <code>year</code>, <code>month</code>, and
   * <code>date</code> arguments.
   *
   * @param year the year minus 1900.
   * @param month the month between 0-11.
   * @param date the day of the month between 1-31.
   * @see java.util.Calendar
   * @deprecated As of JDK version 1.1, replaced by <code>Calendar.set(year + 1900, month,
   * date)</code> or <code>GregorianCalendar(year + 1900, month, date)</code>.
   */
  @Deprecated
  public Date(int year, int month, int date) {
    this(year, month, date, 0, 0, 0);
  }

  /**
   * Allocates a <code>Date</code> object and initializes it so that
   * it represents the instant at the start of the minute specified by
   * the <code>year</code>, <code>month</code>, <code>date</code>,
   * <code>hrs</code>, and <code>min</code> arguments, in the local
   * time zone.
   *
   * @param year the year minus 1900.
   * @param month the month between 0-11.
   * @param date the day of the month between 1-31.
   * @param hrs the hours between 0-23.
   * @param min the minutes between 0-59.
   * @see java.util.Calendar
   * @deprecated As of JDK version 1.1, replaced by <code>Calendar.set(year + 1900, month, date,
   * hrs, min)</code> or <code>GregorianCalendar(year + 1900, month, date, hrs, min)</code>.
   */
  @Deprecated
  public Date(int year, int month, int date, int hrs, int min) {
    this(year, month, date, hrs, min, 0);
  }

  /**
   * Allocates a <code>Date</code> object and initializes it so that
   * it represents the instant at the start of the second specified
   * by the <code>year</code>, <code>month</code>, <code>date</code>,
   * <code>hrs</code>, <code>min</code>, and <code>sec</code> arguments,
   * in the local time zone.
   *
   * @param year the year minus 1900.
   * @param month the month between 0-11.
   * @param date the day of the month between 1-31.
   * @param hrs the hours between 0-23.
   * @param min the minutes between 0-59.
   * @param sec the seconds between 0-59.
   * @see java.util.Calendar
   * @deprecated As of JDK version 1.1, replaced by <code>Calendar.set(year + 1900, month, date,
   * hrs, min, sec)</code> or <code>GregorianCalendar(year + 1900, month, date, hrs, min,
   * sec)</code>.
   */
  @Deprecated
  public Date(int year, int month, int date, int hrs, int min, int sec) {
    int y = year + 1900;
    // month is 0-based. So we have to normalize month to support Long.MAX_VALUE.
    if (month >= 12) {
      y += month / 12;
      month %= 12;
    } else if (month < 0) {
      y += CalendarUtils.floorDivide(month, 12);
      month = CalendarUtils.mod(month, 12);
    }
    BaseCalendar cal = getCalendarSystem(y);
    cdate = (BaseCalendar.Date) cal.newCalendarDate(TimeZone.getDefaultRef());
    cdate.setNormalizedDate(y, month + 1, date).setTimeOfDay(hrs, min, sec, 0);
    getTimeImpl();
    cdate = null;
  }

  /**
   * Allocates a <code>Date</code> object and initializes it so that
   * it represents the date and time indicated by the string
   * <code>s</code>, which is interpreted as if by the
   * {@link Date#parse} method.
   *
   * @param s a string representation of the date.
   * @see java.text.DateFormat
   * @see java.util.Date#parse(java.lang.String)
   * @deprecated As of JDK version 1.1, replaced by <code>DateFormat.parse(String s)</code>.
   */
  @Deprecated
  public Date(String s) {
    this(parse(s));
  }

  /**
   * Return a copy of this object.
   */
  public Object clone() {
    Date d = null;
    try {
      d = (Date) super.clone();
      if (cdate != null) {
        d.cdate = (BaseCalendar.Date) cdate.clone();
      }
    } catch (CloneNotSupportedException e) {
    } // Won't happen
    return d;
  }

  /**
   * Determines the date and time based on the arguments. The
   * arguments are interpreted as a year, month, day of the month,
   * hour of the day, minute within the hour, and second within the
   * minute, exactly as for the <tt>Date</tt> constructor with six
   * arguments, except that the arguments are interpreted relative
   * to UTC rather than to the local time zone. The time indicated is
   * returned represented as the distance, measured in milliseconds,
   * of that time from the epoch (00:00:00 GMT on January 1, 1970).
   *
   * @param year the year minus 1900.
   * @param month the month between 0-11.
   * @param date the day of the month between 1-31.
   * @param hrs the hours between 0-23.
   * @param min the minutes between 0-59.
   * @param sec the seconds between 0-59.
   * @return the number of milliseconds since January 1, 1970, 00:00:00 GMT for the date and time
   * specified by the arguments.
   * @see java.util.Calendar
   * @deprecated As of JDK version 1.1, replaced by <code>Calendar.set(year + 1900, month, date,
   * hrs, min, sec)</code> or <code>GregorianCalendar(year + 1900, month, date, hrs, min,
   * sec)</code>, using a UTC <code>TimeZone</code>, followed by <code>Calendar.getTime().getTime()</code>.
   */
  @Deprecated
  public static long UTC(int year, int month, int date,
      int hrs, int min, int sec) {
    int y = year + 1900;
    // month is 0-based. So we have to normalize month to support Long.MAX_VALUE.
    if (month >= 12) {
      y += month / 12;
      month %= 12;
    } else if (month < 0) {
      y += CalendarUtils.floorDivide(month, 12);
      month = CalendarUtils.mod(month, 12);
    }
    int m = month + 1;
    BaseCalendar cal = getCalendarSystem(y);
    BaseCalendar.Date udate = (BaseCalendar.Date) cal.newCalendarDate(null);
    udate.setNormalizedDate(y, m, date).setTimeOfDay(hrs, min, sec, 0);

    // Use a Date instance to perform normalization. Its fastTime
    // is the UTC value after the normalization.
    Date d = new Date(0);
    d.normalize(udate);
    return d.fastTime;
  }

  /**
   * Attempts to interpret the string <tt>s</tt> as a representation
   * of a date and time. If the attempt is successful, the time
   * indicated is returned represented as the distance, measured in
   * milliseconds, of that time from the epoch (00:00:00 GMT on
   * January 1, 1970). If the attempt fails, an
   * <tt>IllegalArgumentException</tt> is thrown.
   * <p>
   * It accepts many syntaxes; in particular, it recognizes the IETF
   * standard date syntax: "Sat, 12 Aug 1995 13:30:00 GMT". It also
   * understands the continental U.S. time-zone abbreviations, but for
   * general use, a time-zone offset should be used: "Sat, 12 Aug 1995
   * 13:30:00 GMT+0430" (4 hours, 30 minutes west of the Greenwich
   * meridian). If no time zone is specified, the local time zone is
   * assumed. GMT and UTC are considered equivalent.
   * <p>
   * The string <tt>s</tt> is processed from left to right, looking for
   * data of interest. Any material in <tt>s</tt> that is within the
   * ASCII parenthesis characters <tt>(</tt> and <tt>)</tt> is ignored.
   * Parentheses may be nested. Otherwise, the only characters permitted
   * within <tt>s</tt> are these ASCII characters:
   * <blockquote><pre>
   * abcdefghijklmnopqrstuvwxyz
   * ABCDEFGHIJKLMNOPQRSTUVWXYZ
   * 0123456789,+-:/</pre></blockquote>
   * and whitespace characters.<p>
   * A consecutive sequence of decimal digits is treated as a decimal
   * number:<ul>
   * <li>If a number is preceded by <tt>+</tt> or <tt>-</tt> and a year
   * has already been recognized, then the number is a time-zone
   * offset. If the number is less than 24, it is an offset measured
   * in hours. Otherwise, it is regarded as an offset in minutes,
   * expressed in 24-hour time format without punctuation. A
   * preceding <tt>-</tt> means a westward offset. Time zone offsets
   * are always relative to UTC (Greenwich). Thus, for example,
   * <tt>-5</tt> occurring in the string would mean "five hours west
   * of Greenwich" and <tt>+0430</tt> would mean "four hours and
   * thirty minutes east of Greenwich." It is permitted for the
   * string to specify <tt>GMT</tt>, <tt>UT</tt>, or <tt>UTC</tt>
   * redundantly-for example, <tt>GMT-5</tt> or <tt>utc+0430</tt>.
   * <li>The number is regarded as a year number if one of the
   * following conditions is true:
   * <ul>
   * <li>The number is equal to or greater than 70 and followed by a
   * space, comma, slash, or end of string
   * <li>The number is less than 70, and both a month and a day of
   * the month have already been recognized</li>
   * </ul>
   * If the recognized year number is less than 100, it is
   * interpreted as an abbreviated year relative to a century of
   * which dates are within 80 years before and 19 years after
   * the time when the Date class is initialized.
   * After adjusting the year number, 1900 is subtracted from
   * it. For example, if the current year is 1999 then years in
   * the range 19 to 99 are assumed to mean 1919 to 1999, while
   * years from 0 to 18 are assumed to mean 2000 to 2018.  Note
   * that this is slightly different from the interpretation of
   * years less than 100 that is used in {@link java.text.SimpleDateFormat}.
   * <li>If the number is followed by a colon, it is regarded as an hour,
   * unless an hour has already been recognized, in which case it is
   * regarded as a minute.
   * <li>If the number is followed by a slash, it is regarded as a month
   * (it is decreased by 1 to produce a number in the range <tt>0</tt>
   * to <tt>11</tt>), unless a month has already been recognized, in
   * which case it is regarded as a day of the month.
   * <li>If the number is followed by whitespace, a comma, a hyphen, or
   * end of string, then if an hour has been recognized but not a
   * minute, it is regarded as a minute; otherwise, if a minute has
   * been recognized but not a second, it is regarded as a second;
   * otherwise, it is regarded as a day of the month. </ul><p>
   * A consecutive sequence of letters is regarded as a word and treated
   * as follows:<ul>
   * <li>A word that matches <tt>AM</tt>, ignoring case, is ignored (but
   * the parse fails if an hour has not been recognized or is less
   * than <tt>1</tt> or greater than <tt>12</tt>).
   * <li>A word that matches <tt>PM</tt>, ignoring case, adds <tt>12</tt>
   * to the hour (but the parse fails if an hour has not been
   * recognized or is less than <tt>1</tt> or greater than <tt>12</tt>).
   * <li>Any word that matches any prefix of <tt>SUNDAY, MONDAY, TUESDAY,
   * WEDNESDAY, THURSDAY, FRIDAY</tt>, or <tt>SATURDAY</tt>, ignoring
   * case, is ignored. For example, <tt>sat, Friday, TUE</tt>, and
   * <tt>Thurs</tt> are ignored.
   * <li>Otherwise, any word that matches any prefix of <tt>JANUARY,
   * FEBRUARY, MARCH, APRIL, MAY, JUNE, JULY, AUGUST, SEPTEMBER,
   * OCTOBER, NOVEMBER</tt>, or <tt>DECEMBER</tt>, ignoring case, and
   * considering them in the order given here, is recognized as
   * specifying a month and is converted to a number (<tt>0</tt> to
   * <tt>11</tt>). For example, <tt>aug, Sept, april</tt>, and
   * <tt>NOV</tt> are recognized as months. So is <tt>Ma</tt>, which
   * is recognized as <tt>MARCH</tt>, not <tt>MAY</tt>.
   * <li>Any word that matches <tt>GMT, UT</tt>, or <tt>UTC</tt>, ignoring
   * case, is treated as referring to UTC.
   * <li>Any word that matches <tt>EST, CST, MST</tt>, or <tt>PST</tt>,
   * ignoring case, is recognized as referring to the time zone in
   * North America that is five, six, seven, or eight hours west of
   * Greenwich, respectively. Any word that matches <tt>EDT, CDT,
   * MDT</tt>, or <tt>PDT</tt>, ignoring case, is recognized as
   * referring to the same time zone, respectively, during daylight
   * saving time.</ul><p>
   * Once the entire string s has been scanned, it is converted to a time
   * result in one of two ways. If a time zone or time-zone offset has been
   * recognized, then the year, month, day of month, hour, minute, and
   * second are interpreted in UTC and then the time-zone offset is
   * applied. Otherwise, the year, month, day of month, hour, minute, and
   * second are interpreted in the local time zone.
   *
   * @param s a string to be parsed as a date.
   * @return the number of milliseconds since January 1, 1970, 00:00:00 GMT represented by the
   * string argument.
   * @see java.text.DateFormat
   * @deprecated As of JDK version 1.1, replaced by <code>DateFormat.parse(String s)</code>.
   */
  @Deprecated
  public static long parse(String s) {
    int year = Integer.MIN_VALUE;
    int mon = -1;
    int mday = -1;
    int hour = -1;
    int min = -1;
    int sec = -1;
    int millis = -1;
    int c = -1;
    int i = 0;
    int n = -1;
    int wst = -1;
    int tzoffset = -1;
    int prevc = 0;
    syntax:
    {
      if (s == null) {
        break syntax;
      }
      int limit = s.length();
      while (i < limit) {
        c = s.charAt(i);
        i++;
        if (c <= ' ' || c == ',') {
          continue;
        }
        if (c == '(') { // skip comments
          int depth = 1;
          while (i < limit) {
            c = s.charAt(i);
            i++;
            if (c == '(') {
              depth++;
            } else if (c == ')') {
              if (--depth <= 0) {
                break;
              }
            }
          }
          continue;
        }
        if ('0' <= c && c <= '9') {
          n = c - '0';
          while (i < limit && '0' <= (c = s.charAt(i)) && c <= '9') {
            n = n * 10 + c - '0';
            i++;
          }
          if (prevc == '+' || prevc == '-' && year != Integer.MIN_VALUE) {
            // timezone offset
            if (n < 24) {
              n = n * 60; // EG. "GMT-3"
            } else {
              n = n % 100 + n / 100 * 60; // eg "GMT-0430"
            }
            if (prevc == '+')   // plus means east of GMT
            {
              n = -n;
            }
            if (tzoffset != 0 && tzoffset != -1) {
              break syntax;
            }
            tzoffset = n;
          } else if (n >= 70) {
            if (year != Integer.MIN_VALUE) {
              break syntax;
            } else if (c <= ' ' || c == ',' || c == '/' || i >= limit)
            // year = n < 1900 ? n : n - 1900;
            {
              year = n;
            } else {
              break syntax;
            }
          } else if (c == ':') {
            if (hour < 0) {
              hour = (byte) n;
            } else if (min < 0) {
              min = (byte) n;
            } else {
              break syntax;
            }
          } else if (c == '/') {
            if (mon < 0) {
              mon = (byte) (n - 1);
            } else if (mday < 0) {
              mday = (byte) n;
            } else {
              break syntax;
            }
          } else if (i < limit && c != ',' && c > ' ' && c != '-') {
            break syntax;
          } else if (hour >= 0 && min < 0) {
            min = (byte) n;
          } else if (min >= 0 && sec < 0) {
            sec = (byte) n;
          } else if (mday < 0) {
            mday = (byte) n;
          }
          // Handle two-digit years < 70 (70-99 handled above).
          else if (year == Integer.MIN_VALUE && mon >= 0 && mday >= 0) {
            year = n;
          } else {
            break syntax;
          }
          prevc = 0;
        } else if (c == '/' || c == ':' || c == '+' || c == '-') {
          prevc = c;
        } else {
          int st = i - 1;
          while (i < limit) {
            c = s.charAt(i);
            if (!('A' <= c && c <= 'Z' || 'a' <= c && c <= 'z')) {
              break;
            }
            i++;
          }
          if (i <= st + 1) {
            break syntax;
          }
          int k;
          for (k = wtb.length; --k >= 0; ) {
            if (wtb[k].regionMatches(true, 0, s, st, i - st)) {
              int action = ttb[k];
              if (action != 0) {
                if (action == 1) {  // pm
                  if (hour > 12 || hour < 1) {
                    break syntax;
                  } else if (hour < 12) {
                    hour += 12;
                  }
                } else if (action == 14) {  // am
                  if (hour > 12 || hour < 1) {
                    break syntax;
                  } else if (hour == 12) {
                    hour = 0;
                  }
                } else if (action <= 13) {  // month!
                  if (mon < 0) {
                    mon = (byte) (action - 2);
                  } else {
                    break syntax;
                  }
                } else {
                  tzoffset = action - 10000;
                }
              }
              break;
            }
          }
          if (k < 0) {
            break syntax;
          }
          prevc = 0;
        }
      }
      if (year == Integer.MIN_VALUE || mon < 0 || mday < 0) {
        break syntax;
      }
      // Parse 2-digit years within the correct default century.
      if (year < 100) {
        synchronized (Date.class) {
          if (defaultCenturyStart == 0) {
            defaultCenturyStart = gcal.getCalendarDate().getYear() - 80;
          }
        }
        year += (defaultCenturyStart / 100) * 100;
        if (year < defaultCenturyStart) {
          year += 100;
        }
      }
      if (sec < 0) {
        sec = 0;
      }
      if (min < 0) {
        min = 0;
      }
      if (hour < 0) {
        hour = 0;
      }
      BaseCalendar cal = getCalendarSystem(year);
      if (tzoffset == -1) { // no time zone specified, have to use local
        BaseCalendar.Date ldate = (BaseCalendar.Date) cal.newCalendarDate(TimeZone.getDefaultRef());
        ldate.setDate(year, mon + 1, mday);
        ldate.setTimeOfDay(hour, min, sec, 0);
        return cal.getTime(ldate);
      }
      BaseCalendar.Date udate = (BaseCalendar.Date) cal.newCalendarDate(null); // no time zone
      udate.setDate(year, mon + 1, mday);
      udate.setTimeOfDay(hour, min, sec, 0);
      return cal.getTime(udate) + tzoffset * (60 * 1000);
    }
    // syntax error
    throw new IllegalArgumentException();
  }

  private final static String wtb[] = {
      "am", "pm",
      "monday", "tuesday", "wednesday", "thursday", "friday",
      "saturday", "sunday",
      "january", "february", "march", "april", "may", "june",
      "july", "august", "september", "october", "november", "december",
      "gmt", "ut", "utc", "est", "edt", "cst", "cdt",
      "mst", "mdt", "pst", "pdt"
  };
  private final static int ttb[] = {
      14, 1, 0, 0, 0, 0, 0, 0, 0,
      2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,
      10000 + 0, 10000 + 0, 10000 + 0,    // GMT/UT/UTC
      10000 + 5 * 60, 10000 + 4 * 60,     // EST/EDT
      10000 + 6 * 60, 10000 + 5 * 60,     // CST/CDT
      10000 + 7 * 60, 10000 + 6 * 60,     // MST/MDT
      10000 + 8 * 60, 10000 + 7 * 60      // PST/PDT
  };

  /**
   * Returns a value that is the result of subtracting 1900 from the
   * year that contains or begins with the instant in time represented
   * by this <code>Date</code> object, as interpreted in the local
   * time zone.
   *
   * @return the year represented by this date, minus 1900.
   * @see java.util.Calendar
   * @deprecated As of JDK version 1.1, replaced by <code>Calendar.get(Calendar.YEAR) - 1900</code>.
   */
  @Deprecated
  public int getYear() {
    return normalize().getYear() - 1900;
  }

  /**
   * Sets the year of this <tt>Date</tt> object to be the specified
   * value plus 1900. This <code>Date</code> object is modified so
   * that it represents a point in time within the specified year,
   * with the month, date, hour, minute, and second the same as
   * before, as interpreted in the local time zone. (Of course, if
   * the date was February 29, for example, and the year is set to a
   * non-leap year, then the new date will be treated as if it were
   * on March 1.)
   *
   * @param year the year value.
   * @see java.util.Calendar
   * @deprecated As of JDK version 1.1, replaced by <code>Calendar.set(Calendar.YEAR, year +
   * 1900)</code>.
   */
  @Deprecated
  public void setYear(int year) {
    getCalendarDate().setNormalizedYear(year + 1900);
  }

  /**
   * Returns a number representing the month that contains or begins
   * with the instant in time represented by this <tt>Date</tt> object.
   * The value returned is between <code>0</code> and <code>11</code>,
   * with the value <code>0</code> representing January.
   *
   * @return the month represented by this date.
   * @see java.util.Calendar
   * @deprecated As of JDK version 1.1, replaced by <code>Calendar.get(Calendar.MONTH)</code>.
   */
  @Deprecated
  public int getMonth() {
    return normalize().getMonth() - 1; // adjust 1-based to 0-based
  }

  /**
   * Sets the month of this date to the specified value. This
   * <tt>Date</tt> object is modified so that it represents a point
   * in time within the specified month, with the year, date, hour,
   * minute, and second the same as before, as interpreted in the
   * local time zone. If the date was October 31, for example, and
   * the month is set to June, then the new date will be treated as
   * if it were on July 1, because June has only 30 days.
   *
   * @param month the month value between 0-11.
   * @see java.util.Calendar
   * @deprecated As of JDK version 1.1, replaced by <code>Calendar.set(Calendar.MONTH, int
   * month)</code>.
   */
  @Deprecated
  public void setMonth(int month) {
    int y = 0;
    if (month >= 12) {
      y = month / 12;
      month %= 12;
    } else if (month < 0) {
      y = CalendarUtils.floorDivide(month, 12);
      month = CalendarUtils.mod(month, 12);
    }
    BaseCalendar.Date d = getCalendarDate();
    if (y != 0) {
      d.setNormalizedYear(d.getNormalizedYear() + y);
    }
    d.setMonth(month + 1); // adjust 0-based to 1-based month numbering
  }

  /**
   * Returns the day of the month represented by this <tt>Date</tt> object.
   * The value returned is between <code>1</code> and <code>31</code>
   * representing the day of the month that contains or begins with the
   * instant in time represented by this <tt>Date</tt> object, as
   * interpreted in the local time zone.
   *
   * @return the day of the month represented by this date.
   * @see java.util.Calendar
   * @deprecated
   */
  @Deprecated
  public int getDate() {
    return normalize().getDayOfMonth();
  }

  /**
   * Sets the day of the month of this <tt>Date</tt> object to the
   * specified value. This <tt>Date</tt> object is modified so that
   * it represents a point in time within the specified day of the
   * month, with the year, month, hour, minute, and second the same
   * as before, as interpreted in the local time zone. If the date
   * was April 30, for example, and the date is set to 31, then it
   * will be treated as if it were on May 1, because April has only
   * 30 days.
   *
   * @param date the day of the month value between 1-31.
   * @see java.util.Calendar
   * @deprecated As of JDK version 1.1, replaced by <code>Calendar.set(Calendar.DAY_OF_MONTH, int
   * date)</code>.
   */
  @Deprecated
  public void setDate(int date) {
    getCalendarDate().setDayOfMonth(date);
  }

  /**
   * Returns the day of the week represented by this date. The
   * returned value (<tt>0</tt> = Sunday, <tt>1</tt> = Monday,
   * <tt>2</tt> = Tuesday, <tt>3</tt> = Wednesday, <tt>4</tt> =
   * Thursday, <tt>5</tt> = Friday, <tt>6</tt> = Saturday)
   * represents the day of the week that contains or begins with
   * the instant in time represented by this <tt>Date</tt> object,
   * as interpreted in the local time zone.
   *
   * @return the day of the week represented by this date.
   * @see java.util.Calendar
   * @deprecated As of JDK version 1.1, replaced by <code>Calendar.get(Calendar.DAY_OF_WEEK)</code>.
   */
  @Deprecated
  public int getDay() {
    return normalize().getDayOfWeek() - BaseCalendar.SUNDAY;
  }

  /**
   * Returns the hour represented by this <tt>Date</tt> object. The
   * returned value is a number (<tt>0</tt> through <tt>23</tt>)
   * representing the hour within the day that contains or begins
   * with the instant in time represented by this <tt>Date</tt>
   * object, as interpreted in the local time zone.
   *
   * @return the hour represented by this date.
   * @see java.util.Calendar
   * @deprecated As of JDK version 1.1, replaced by <code>Calendar.get(Calendar.HOUR_OF_DAY)</code>.
   */
  @Deprecated
  public int getHours() {
    return normalize().getHours();
  }

  /**
   * Sets the hour of this <tt>Date</tt> object to the specified value.
   * This <tt>Date</tt> object is modified so that it represents a point
   * in time within the specified hour of the day, with the year, month,
   * date, minute, and second the same as before, as interpreted in the
   * local time zone.
   *
   * @param hours the hour value.
   * @see java.util.Calendar
   * @deprecated As of JDK version 1.1, replaced by <code>Calendar.set(Calendar.HOUR_OF_DAY, int
   * hours)</code>.
   */
  @Deprecated
  public void setHours(int hours) {
    getCalendarDate().setHours(hours);
  }

  /**
   * Returns the number of minutes past the hour represented by this date,
   * as interpreted in the local time zone.
   * The value returned is between <code>0</code> and <code>59</code>.
   *
   * @return the number of minutes past the hour represented by this date.
   * @see java.util.Calendar
   * @deprecated As of JDK version 1.1, replaced by <code>Calendar.get(Calendar.MINUTE)</code>.
   */
  @Deprecated
  public int getMinutes() {
    return normalize().getMinutes();
  }

  /**
   * Sets the minutes of this <tt>Date</tt> object to the specified value.
   * This <tt>Date</tt> object is modified so that it represents a point
   * in time within the specified minute of the hour, with the year, month,
   * date, hour, and second the same as before, as interpreted in the
   * local time zone.
   *
   * @param minutes the value of the minutes.
   * @see java.util.Calendar
   * @deprecated As of JDK version 1.1, replaced by <code>Calendar.set(Calendar.MINUTE, int
   * minutes)</code>.
   */
  @Deprecated
  public void setMinutes(int minutes) {
    getCalendarDate().setMinutes(minutes);
  }

  /**
   * Returns the number of seconds past the minute represented by this date.
   * The value returned is between <code>0</code> and <code>61</code>. The
   * values <code>60</code> and <code>61</code> can only occur on those
   * Java Virtual Machines that take leap seconds into account.
   *
   * @return the number of seconds past the minute represented by this date.
   * @see java.util.Calendar
   * @deprecated As of JDK version 1.1, replaced by <code>Calendar.get(Calendar.SECOND)</code>.
   */
  @Deprecated
  public int getSeconds() {
    return normalize().getSeconds();
  }

  /**
   * Sets the seconds of this <tt>Date</tt> to the specified value.
   * This <tt>Date</tt> object is modified so that it represents a
   * point in time within the specified second of the minute, with
   * the year, month, date, hour, and minute the same as before, as
   * interpreted in the local time zone.
   *
   * @param seconds the seconds value.
   * @see java.util.Calendar
   * @deprecated As of JDK version 1.1, replaced by <code>Calendar.set(Calendar.SECOND, int
   * seconds)</code>.
   */
  @Deprecated
  public void setSeconds(int seconds) {
    getCalendarDate().setSeconds(seconds);
  }

  /**
   * Returns the number of milliseconds since January 1, 1970, 00:00:00 GMT
   * represented by this <tt>Date</tt> object.
   *
   * @return the number of milliseconds since January 1, 1970, 00:00:00 GMT represented by this
   * date.
   */
  public long getTime() {
    return getTimeImpl();
  }

  private final long getTimeImpl() {
    if (cdate != null && !cdate.isNormalized()) {
      normalize();
    }
    return fastTime;
  }

  /**
   * Sets this <code>Date</code> object to represent a point in time that is
   * <code>time</code> milliseconds after January 1, 1970 00:00:00 GMT.
   *
   * @param time the number of milliseconds.
   */
  public void setTime(long time) {
    fastTime = time;
    cdate = null;
  }

  /**
   * Tests if this date is before the specified date.
   *
   * @param when a date.
   * @return <code>true</code> if and only if the instant of time represented by this <tt>Date</tt>
   * object is strictly earlier than the instant represented by <tt>when</tt>; <code>false</code>
   * otherwise.
   * @throws NullPointerException if <code>when</code> is null.
   */
  public boolean before(Date when) {
    return getMillisOf(this) < getMillisOf(when);
  }

  /**
   * Tests if this date is after the specified date.
   *
   * @param when a date.
   * @return <code>true</code> if and only if the instant represented by this <tt>Date</tt> object
   * is strictly later than the instant represented by <tt>when</tt>; <code>false</code> otherwise.
   * @throws NullPointerException if <code>when</code> is null.
   */
  public boolean after(Date when) {
    return getMillisOf(this) > getMillisOf(when);
  }

  /**
   * Compares two dates for equality.
   * The result is <code>true</code> if and only if the argument is
   * not <code>null</code> and is a <code>Date</code> object that
   * represents the same point in time, to the millisecond, as this object.
   * <p>
   * Thus, two <code>Date</code> objects are equal if and only if the
   * <code>getTime</code> method returns the same <code>long</code>
   * value for both.
   *
   * @param obj the object to compare with.
   * @return <code>true</code> if the objects are the same; <code>false</code> otherwise.
   * @see java.util.Date#getTime()
   */
  public boolean equals(Object obj) {
    return obj instanceof Date && getTime() == ((Date) obj).getTime();
  }

  /**
   * Returns the millisecond value of this <code>Date</code> object
   * without affecting its internal state.
   */
  static final long getMillisOf(Date date) {
    if (date.cdate == null || date.cdate.isNormalized()) {
      return date.fastTime;
    }
    BaseCalendar.Date d = (BaseCalendar.Date) date.cdate.clone();
    return gcal.getTime(d);
  }

  /**
   * Compares two Dates for ordering.
   *
   * @param anotherDate the <code>Date</code> to be compared.
   * @return the value <code>0</code> if the argument Date is equal to this Date; a value less than
   * <code>0</code> if this Date is before the Date argument; and a value greater than
   * <code>0</code> if this Date is after the Date argument.
   * @throws NullPointerException if <code>anotherDate</code> is null.
   * @since 1.2
   */
  public int compareTo(Date anotherDate) {
    long thisTime = getMillisOf(this);
    long anotherTime = getMillisOf(anotherDate);
    return (thisTime < anotherTime ? -1 : (thisTime == anotherTime ? 0 : 1));
  }

  /**
   * Returns a hash code value for this object. The result is the
   * exclusive OR of the two halves of the primitive <tt>long</tt>
   * value returned by the {@link Date#getTime}
   * method. That is, the hash code is the value of the expression:
   * <blockquote><pre>{@code
   * (int)(this.getTime()^(this.getTime() >>> 32))
   * }</pre></blockquote>
   *
   * @return a hash code value for this object.
   */
  public int hashCode() {
    long ht = this.getTime();
    return (int) ht ^ (int) (ht >> 32);
  }

  /**
   * Converts this <code>Date</code> object to a <code>String</code>
   * of the form:
   * <blockquote><pre>
   * dow mon dd hh:mm:ss zzz yyyy</pre></blockquote>
   * where:<ul>
   * <li><tt>dow</tt> is the day of the week (<tt>Sun, Mon, Tue, Wed,
   * Thu, Fri, Sat</tt>).
   * <li><tt>mon</tt> is the month (<tt>Jan, Feb, Mar, Apr, May, Jun,
   * Jul, Aug, Sep, Oct, Nov, Dec</tt>).
   * <li><tt>dd</tt> is the day of the month (<tt>01</tt> through
   * <tt>31</tt>), as two decimal digits.
   * <li><tt>hh</tt> is the hour of the day (<tt>00</tt> through
   * <tt>23</tt>), as two decimal digits.
   * <li><tt>mm</tt> is the minute within the hour (<tt>00</tt> through
   * <tt>59</tt>), as two decimal digits.
   * <li><tt>ss</tt> is the second within the minute (<tt>00</tt> through
   * <tt>61</tt>, as two decimal digits.
   * <li><tt>zzz</tt> is the time zone (and may reflect daylight saving
   * time). Standard time zone abbreviations include those
   * recognized by the method <tt>parse</tt>. If time zone
   * information is not available, then <tt>zzz</tt> is empty -
   * that is, it consists of no characters at all.
   * <li><tt>yyyy</tt> is the year, as four decimal digits.
   * </ul>
   *
   * @return a string representation of this date.
   * @see java.util.Date#toLocaleString()
   * @see java.util.Date#toGMTString()
   */
  public String toString() {
    // "EEE MMM dd HH:mm:ss zzz yyyy";
    BaseCalendar.Date date = normalize();
    StringBuilder sb = new StringBuilder(28);
    int index = date.getDayOfWeek();
    if (index == BaseCalendar.SUNDAY) {
      index = 8;
    }
    convertToAbbr(sb, wtb[index]).append(' ');                        // EEE
    convertToAbbr(sb, wtb[date.getMonth() - 1 + 2 + 7]).append(' ');  // MMM
    CalendarUtils.sprintf0d(sb, date.getDayOfMonth(), 2).append(' '); // dd

    CalendarUtils.sprintf0d(sb, date.getHours(), 2).append(':');   // HH
    CalendarUtils.sprintf0d(sb, date.getMinutes(), 2).append(':'); // mm
    CalendarUtils.sprintf0d(sb, date.getSeconds(), 2).append(' '); // ss
    TimeZone zi = date.getZone();
    if (zi != null) {
      sb.append(zi.getDisplayName(date.isDaylightTime(), TimeZone.SHORT, Locale.US)); // zzz
    } else {
      sb.append("GMT");
    }
    sb.append(' ').append(date.getYear());  // yyyy
    return sb.toString();
  }

  /**
   * Converts the given name to its 3-letter abbreviation (e.g.,
   * "monday" -> "Mon") and stored the abbreviation in the given
   * <code>StringBuilder</code>.
   */
  private static final StringBuilder convertToAbbr(StringBuilder sb, String name) {
    sb.append(Character.toUpperCase(name.charAt(0)));
    sb.append(name.charAt(1)).append(name.charAt(2));
    return sb;
  }

  /**
   * Creates a string representation of this <tt>Date</tt> object in an
   * implementation-dependent form. The intent is that the form should
   * be familiar to the user of the Java application, wherever it may
   * happen to be running. The intent is comparable to that of the
   * "<code>%c</code>" format supported by the <code>strftime()</code>
   * function of ISO&nbsp;C.
   *
   * @return a string representation of this date, using the locale conventions.
   * @see java.text.DateFormat
   * @see java.util.Date#toString()
   * @see java.util.Date#toGMTString()
   * @deprecated As of JDK version 1.1, replaced by <code>DateFormat.format(Date date)</code>.
   */
  @Deprecated
  public String toLocaleString() {
    DateFormat formatter = DateFormat.getDateTimeInstance();
    return formatter.format(this);
  }

  /**
   * Creates a string representation of this <tt>Date</tt> object of
   * the form:
   * <blockquote><pre>
   * d mon yyyy hh:mm:ss GMT</pre></blockquote>
   * where:<ul>
   * <li><i>d</i> is the day of the month (<tt>1</tt> through <tt>31</tt>),
   * as one or two decimal digits.
   * <li><i>mon</i> is the month (<tt>Jan, Feb, Mar, Apr, May, Jun, Jul,
   * Aug, Sep, Oct, Nov, Dec</tt>).
   * <li><i>yyyy</i> is the year, as four decimal digits.
   * <li><i>hh</i> is the hour of the day (<tt>00</tt> through <tt>23</tt>),
   * as two decimal digits.
   * <li><i>mm</i> is the minute within the hour (<tt>00</tt> through
   * <tt>59</tt>), as two decimal digits.
   * <li><i>ss</i> is the second within the minute (<tt>00</tt> through
   * <tt>61</tt>), as two decimal digits.
   * <li><i>GMT</i> is exactly the ASCII letters "<tt>GMT</tt>" to indicate
   * Greenwich Mean Time.
   * </ul><p>
   * The result does not depend on the local time zone.
   *
   * @return a string representation of this date, using the Internet GMT conventions.
   * @see java.text.DateFormat
   * @see java.util.Date#toString()
   * @see java.util.Date#toLocaleString()
   * @deprecated As of JDK version 1.1, replaced by <code>DateFormat.format(Date date)</code>, using
   * a GMT <code>TimeZone</code>.
   */
  @Deprecated
  public String toGMTString() {
    // d MMM yyyy HH:mm:ss 'GMT'
    long t = getTime();
    BaseCalendar cal = getCalendarSystem(t);
    BaseCalendar.Date date =
        (BaseCalendar.Date) cal.getCalendarDate(getTime(), (TimeZone) null);
    StringBuilder sb = new StringBuilder(32);
    CalendarUtils.sprintf0d(sb, date.getDayOfMonth(), 1).append(' '); // d
    convertToAbbr(sb, wtb[date.getMonth() - 1 + 2 + 7]).append(' ');  // MMM
    sb.append(date.getYear()).append(' ');                            // yyyy
    CalendarUtils.sprintf0d(sb, date.getHours(), 2).append(':');      // HH
    CalendarUtils.sprintf0d(sb, date.getMinutes(), 2).append(':');    // mm
    CalendarUtils.sprintf0d(sb, date.getSeconds(), 2);                // ss
    sb.append(" GMT");                                                // ' GMT'
    return sb.toString();
  }

  /**
   * Returns the offset, measured in minutes, for the local time zone
   * relative to UTC that is appropriate for the time represented by
   * this <code>Date</code> object.
   * <p>
   * For example, in Massachusetts, five time zones west of Greenwich:
   * <blockquote><pre>
   * new Date(96, 1, 14).getTimezoneOffset() returns 300</pre></blockquote>
   * because on February 14, 1996, standard time (Eastern Standard Time)
   * is in use, which is offset five hours from UTC; but:
   * <blockquote><pre>
   * new Date(96, 5, 1).getTimezoneOffset() returns 240</pre></blockquote>
   * because on June 1, 1996, daylight saving time (Eastern Daylight Time)
   * is in use, which is offset only four hours from UTC.<p>
   * This method produces the same result as if it computed:
   * <blockquote><pre>
   * (this.getTime() - UTC(this.getYear(),
   *                       this.getMonth(),
   *                       this.getDate(),
   *                       this.getHours(),
   *                       this.getMinutes(),
   *                       this.getSeconds())) / (60 * 1000)
   * </pre></blockquote>
   *
   * @return the time-zone offset, in minutes, for the current time zone.
   * @see java.util.Calendar#ZONE_OFFSET
   * @see java.util.Calendar#DST_OFFSET
   * @see java.util.TimeZone#getDefault
   * @deprecated As of JDK version 1.1, replaced by <code>-(Calendar.get(Calendar.ZONE_OFFSET) +
   * Calendar.get(Calendar.DST_OFFSET)) / (60 * 1000)</code>.
   */
  @Deprecated
  public int getTimezoneOffset() {
    int zoneOffset;
    if (cdate == null) {
      TimeZone tz = TimeZone.getDefaultRef();
      if (tz instanceof ZoneInfo) {
        zoneOffset = ((ZoneInfo) tz).getOffsets(fastTime, null);
      } else {
        zoneOffset = tz.getOffset(fastTime);
      }
    } else {
      normalize();
      zoneOffset = cdate.getZoneOffset();
    }
    return -zoneOffset / 60000;  // convert to minutes
  }

  private final BaseCalendar.Date getCalendarDate() {
    if (cdate == null) {
      BaseCalendar cal = getCalendarSystem(fastTime);
      cdate = (BaseCalendar.Date) cal.getCalendarDate(fastTime,
          TimeZone.getDefaultRef());
    }
    return cdate;
  }

  private final BaseCalendar.Date normalize() {
    if (cdate == null) {
      BaseCalendar cal = getCalendarSystem(fastTime);
      cdate = (BaseCalendar.Date) cal.getCalendarDate(fastTime,
          TimeZone.getDefaultRef());
      return cdate;
    }

    // Normalize cdate with the TimeZone in cdate first. This is
    // required for the compatible behavior.
    if (!cdate.isNormalized()) {
      cdate = normalize(cdate);
    }

    // If the default TimeZone has changed, then recalculate the
    // fields with the new TimeZone.
    TimeZone tz = TimeZone.getDefaultRef();
    if (tz != cdate.getZone()) {
      cdate.setZone(tz);
      CalendarSystem cal = getCalendarSystem(cdate);
      cal.getCalendarDate(fastTime, cdate);
    }
    return cdate;
  }

  // fastTime and the returned data are in sync upon return.
  private final BaseCalendar.Date normalize(BaseCalendar.Date date) {
    int y = date.getNormalizedYear();
    int m = date.getMonth();
    int d = date.getDayOfMonth();
    int hh = date.getHours();
    int mm = date.getMinutes();
    int ss = date.getSeconds();
    int ms = date.getMillis();
    TimeZone tz = date.getZone();

    // If the specified year can't be handled using a long value
    // in milliseconds, GregorianCalendar is used for full
    // compatibility with underflow and overflow. This is required
    // by some JCK tests. The limits are based max year values -
    // years that can be represented by max values of d, hh, mm,
    // ss and ms. Also, let GregorianCalendar handle the default
    // cutover year so that we don't need to worry about the
    // transition here.
    if (y == 1582 || y > 280000000 || y < -280000000) {
      if (tz == null) {
        tz = TimeZone.getTimeZone("GMT");
      }
      GregorianCalendar gc = new GregorianCalendar(tz);
      gc.clear();
      gc.set(GregorianCalendar.MILLISECOND, ms);
      gc.set(y, m - 1, d, hh, mm, ss);
      fastTime = gc.getTimeInMillis();
      BaseCalendar cal = getCalendarSystem(fastTime);
      date = (BaseCalendar.Date) cal.getCalendarDate(fastTime, tz);
      return date;
    }

    BaseCalendar cal = getCalendarSystem(y);
    if (cal != getCalendarSystem(date)) {
      date = (BaseCalendar.Date) cal.newCalendarDate(tz);
      date.setNormalizedDate(y, m, d).setTimeOfDay(hh, mm, ss, ms);
    }
    // Perform the GregorianCalendar-style normalization.
    fastTime = cal.getTime(date);

    // In case the normalized date requires the other calendar
    // system, we need to recalculate it using the other one.
    BaseCalendar ncal = getCalendarSystem(fastTime);
    if (ncal != cal) {
      date = (BaseCalendar.Date) ncal.newCalendarDate(tz);
      date.setNormalizedDate(y, m, d).setTimeOfDay(hh, mm, ss, ms);
      fastTime = ncal.getTime(date);
    }
    return date;
  }

  /**
   * Returns the Gregorian or Julian calendar system to use with the
   * given date. Use Gregorian from October 15, 1582.
   *
   * @param year normalized calendar year (not -1900)
   * @return the CalendarSystem to use for the specified date
   */
  private static final BaseCalendar getCalendarSystem(int year) {
    if (year >= 1582) {
      return gcal;
    }
    return getJulianCalendar();
  }

  private static final BaseCalendar getCalendarSystem(long utc) {
    // Quickly check if the time stamp given by `utc' is the Epoch
    // or later. If it's before 1970, we convert the cutover to
    // local time to compare.
    if (utc >= 0
        || utc >= GregorianCalendar.DEFAULT_GREGORIAN_CUTOVER
        - TimeZone.getDefaultRef().getOffset(utc)) {
      return gcal;
    }
    return getJulianCalendar();
  }

  private static final BaseCalendar getCalendarSystem(BaseCalendar.Date cdate) {
    if (jcal == null) {
      return gcal;
    }
    if (cdate.getEra() != null) {
      return jcal;
    }
    return gcal;
  }

  synchronized private static final BaseCalendar getJulianCalendar() {
    if (jcal == null) {
      jcal = (BaseCalendar) CalendarSystem.forName("julian");
    }
    return jcal;
  }

  /**
   * Save the state of this object to a stream (i.e., serialize it).
   *
   * @serialData The value returned by <code>getTime()</code> is emitted (long).  This represents
   * the offset from January 1, 1970, 00:00:00 GMT in milliseconds.
   */
  private void writeObject(ObjectOutputStream s)
      throws IOException {
    s.writeLong(getTimeImpl());
  }

  /**
   * Reconstitute this object from a stream (i.e., deserialize it).
   */
  private void readObject(ObjectInputStream s)
      throws IOException, ClassNotFoundException {
    fastTime = s.readLong();
  }

  /**
   * Obtains an instance of {@code Date} from an {@code Instant} object.
   * <p>
   * {@code Instant} uses a precision of nanoseconds, whereas {@code Date}
   * uses a precision of milliseconds.  The conversion will trancate any
   * excess precision information as though the amount in nanoseconds was
   * subject to integer division by one million.
   * <p>
   * {@code Instant} can store points on the time-line further in the future
   * and further in the past than {@code Date}. In this scenario, this method
   * will throw an exception.
   *
   * @param instant the instant to convert
   * @return a {@code Date} representing the same point on the time-line as the provided instant
   * @throws NullPointerException if {@code instant} is null.
   * @throws IllegalArgumentException if the instant is too large to represent as a {@code Date}
   * @since 1.8
   */
  public static Date from(Instant instant) {
    try {
      return new Date(instant.toEpochMilli());
    } catch (ArithmeticException ex) {
      throw new IllegalArgumentException(ex);
    }
  }

  /**
   * Converts this {@code Date} object to an {@code Instant}.
   * <p>
   * The conversion creates an {@code Instant} that represents the same
   * point on the time-line as this {@code Date}.
   *
   * @return an instant representing the same point on the time-line as this {@code Date} object
   * @since 1.8
   */
  public Instant toInstant() {
    return Instant.ofEpochMilli(getTime());
  }
}
